With the increasing demand of gas mixtures, it has become more and more crucial to efficiently produce the gas mixtures. Presently, a certain amount of mixed gas (such as argon-hydrogen) is mixed and sealed in a steel cylinder before being shipped to the user. In this case, if the user desires to use a gas mixture by multi-gases with different percentages, lots of steel cylinders are required to be prepared in the factory, which leads to large space and thus inconvenience for both the factory and the user.
More particular, a conventional plasma torch generally achieves desired plasma flame characteristics by adjusting the plasma gas flow and the working current of the plasma torch according to practical demand, which leads to higher cost due to frequent replacement of electrodes that are easily worn out.
Accordingly, some conventional techniques have been reported to uniformly mix the gases with different densities within a large range. However, it is still difficult to optimize the percentages of gases by the use of T-shaped joints and nozzles.
Conventionally, U.S. Pat. No. 4,793,712 discloses a gas mixer capable of being used in plasma spray coating. The gas mixer uses three filter chambers, each being provided on the wall with pores with different diameters (for example, 60, 45 and 20 microns). These pores are used for directing at least two gas flows to mix the same. One of the two gas flows is hydrogen, helium or pre-mixed hydrogen-helium, while the other is argon, nitrogen or pre-mixed argon-nitrogen. If the user desires a gas mixture comprising hydrogen, helium, argon and nitrogen, pre-mixed hydrogen-helium and pre-mixed argon-nitrogen are further mixed by the gas mixer to produce hydrogen-helium-argon-nitrogen. However, the method for controlling the percentages of gas is not disclosed.
U.S. Pat. No. 6,333,481 B2 discloses a device for generating an arc plasma using a gas mixture of argon-hydrogen or nitrogen-hydrogen for cutting. The gas mixer is provided with two gas inlets for introducing two kinds of gas. Even though it requires external control means to precisely control the percentage of each gas in a gas mixture, the control method and hardware for external control are not presented.
U.S. Pat. No. 7,326,875 B2 discloses a device and a method for producing a gas mixture for performing plasma cutting, wherein the percentage of each gas in the gas mixture is precisely controlled by controlling the flow rate and the pressure of the gas. However, a pressure sensor is required for each gas to detect a pressure signal and a signal processor is required for processing the pressure signal for each gas. Moreover, the patent only provides a gas mixture of argon, nitrogen and hydrogen.
Even though the above-mentioned prior art references disclose some useful techniques on the gas mixer and application thereof, there is still need in providing a multi-gas mixer capable of uniformly mixing gases with arbitrary percentages. Accordingly, the present discloses a multi-gas mixer capable of uniformly mixing gases with arbitrary percentages.